The recent growth of non-evasive surgical techniques has generated an increasing demand for devices capable of delivering a wide variety of therapeutic appliances to a specified location inside a patient's body. An embolic coil is one such therapeutic appliance which is released within an aneurysm pouch in a vessel or the like. The coil promotes the formation of a blood clot therein.
One such device for releasing an embolic coil within a vessel aneurysm is disclosed in U.S. Pat. No. 5,108,407 to Geremia et al. which includes a connector having a fiber optic receiving end and a embolic coil mounting end. Heat releasable adhesive bonds the coil to the mounting end of the connector. Laser energy transmitted through the fiber optic is converted to heat by the connector to cause the release of the adhesive bond between the connector and the coil and thus the release of the coil from the connector. With this device, there is the risk that melted adhesive may be deposited in a patient's bloodstream.
U.S. Pat. No. 5,261,916 to Engelson discloses a pusher-vasoocclusive coil assembly that is advanced through a catheter to a selected site within a vessel. The coil has an enlarged ball at its proximal end. The pusher has a keyway at its distal end that receives the ball in interlocking engagement. The pusher and coil are coupled by placing the ball in the keyway and enclosing the coupled assembly within a coaxial sleeve. The coil-pusher-sleeve assembly is positioned at the vessel site and the sleeve is retracted to allow the ball to move out of the keyway to release the pusher and coil.
U.S. Pat. No. 5,304,195 to Twyford, Jr. et al. discloses a pusher-vasoocclusive coil assembly including a coil carrying a ball on its proximal end and a pusher having a wire carrying a ball on its distal end. The pusher and coil are coupled by placing the balls in an overlapping interlocked position and enclosing the coupled assembly within a coaxial sleeve. The coil-pusher-sleeve assembly is then positioned at the site and the sleeve is retracted to allow the balls to move radially relative to one another to disengage and release the pusher and coil.
U.S. Pat. No. 5,354,295 to Guglielmi et al. discloses an embolic coil releasing device wherein a coil is soldered to a wire and separated therefrom at the vessel site either mechanically or by electrolytic separation.
U.S. Pat. No. 4,512,338 to Balko et al. discloses a device including a wire of shape memory alloy which is inserted into a vessel via a catheter while surrounded by insulation means. The insulation means is then removed and the wire expands into a coil configuration so as to occlude the vessel site.
U.S. Pat. No. 4,994,069 to Ritchart et al. discloses a device including a wire having a stretched, linear shape while being advanced through a catheter to a selected vessel and a helical coil shape when released from the catheter.
Despite the above prior art devices, improvements in efficiency and safety are still being sought. The present invention provides an improved therapeutic appliance releasing device which is efficient and safe to use.